I think we should all speak one language (preferably, the one we're speaking now). The information suddenly marketable to or directly consumable by anyone at any given place will significantly increase.
The existence of diversity is generally a sign of freedom and self-sufficiency: that the people in question were/are free to retain and develop/enrich their own culture, and yet function successfully (enough) in interaction with the broader society, without too much pressure to give up their ways. (See: “melting pot” and “salad bowl”.) Monocultures, monolingualism, monotheism, etc., do have certain advantages too of course, but I hope some can see why diversity is valuable too.
People are all different and why should they not choose to communicate/eat/enjoy themselves as they wish, with all the advantages and disadvantages of their choices?
(Plus in the case of languages there are things which can be said in some and really can't be said in others. My wife, child and I would typically speak multiple languages, sometimes even in the same sentence, in order to convey the nuance of what we wanted to say. Hell, even in English there are things said in discipline-specific jargons that aren't really communicable any other way).
Settling on a "common" or "business" language, though, is entirely possible, and has been done many times in history. No language ever encompassed the whole world, and if one language has it's English, right now. Latin, Arabic, Mandarin, French, English, Spanish... The world has seen its share of common languages used within certain spheres of influence.
unus duo tres quattor quinque six septem octo novem decem ...
Ĉar diverseco estas la bazo de ĉia belo kaj ĉia kreemo. Sin diverseco, vivo estus sensignifa.
> I think we should all speak one language (preferably, the one we're speaking now).
Certe, mi konsentas -- sed nur aldone al vian unikan lokan lingvon. Kaj ne la Anglan, mi petas!
You can see some chinese uptake here: http://esperanto.china.org.cn/
Esperanto is very european in its appearance (both grammar and vocab). This seems to have helped it to gain a userbase, which allows others to adopt it who don't share its background. The regularity of the language helps people even if they have to learn a lot of weird roots and struggle to get the very latinate relative clause system (a lot of English speakers struggle with that too though, because agreement is moribund).
Esperanto havas parolantojn en Cxini, Japanio, Koreio, Indonezio kaj Tajlando. Nedube ankauw aliaj sed cxi tiuj estas tiuj de kiuj mi renkontis esperantistojn, aw en mia lando aw en ilia.
Jene vi povas vidi ion de la cxina uzigxo: http://esperanto.china.org.cn/
Esperanto estas tre ewropa law sia formo (kaj gramatike kaj vorte). Sxajne tio helpis gxin obteni fruajn uzantojn, kiuj instigas ekuzi gxin aliajn kiu ne kunhavas gxian historion. La reguleco de la lingvo helpas homojn ecx se ili devas lerni multajn strangajn radikojn kaj penas kompreni la tre latinan relativan fraz-sistemon (multaj angla-parolantoj devas peni per tiu ankaw, cxar konsento estas mortonta).
What's really made it a worthwhile investment is that it's given me a better understanding of language itself. All languages have idiosyncrasies, including Esperanto -- but Esperanto's idiosyncrasies are unusually consistent, making it really easy to map things onto. So I often find it easier to comprehend some weird construct in (say) Hindi or Japanese by mapping it onto straightforward Esperanto, rather than trying to map it onto an English construct that's probably even weirder.
Plus it's just such an easy win. I can order off a menu and find my way around town in a fair handful of languages, but haven't really gotten much further than that. But I can easily read just about anything in Esperanto, with 1/10th the effort that I've put into any other language. Which is just kinda gratifying to be able to do.
If the above statement sounds wrong, it's because __it is__
We should let other cultures and languages to thrive by themselves; as this is the primary reason of evolution of our business language too. If multiple languages would not suddenly exist, our business language will stop borrowing from other languages and would cease to advance by itself.
Gods no. You'll have to pry my other two languages from my cold, dead tongue. Just the ability to have private conversations in public feels like a superpower. The amazing puns you can make up is also a huge benefit - I can amuse myself all the time.
Plus, you know, cultural diversity, accessing millennia of literature and history etc. But that's the boring stuff /s
English profanity feels unsatisfying/watered-down. I suspect overuse in pop-culture has worn away most of the taboo factor, making it less cathartic.
Good grief.